This proposal is to develop an automatic staining system for high- resolution two-dimensional electrophoresis (2DE) gels. The lack of such a system is a major present limiting factor in the use of 2DE of proteins in drug discovery, drug development, toxicology, and in the systematic development of in vitro substitutes for experimental animals. Only if the same molecular-level results are obtained in vivo and in vitro, can later tests be used with confidence. Since high-level in vivo radio-labelling of large numbers of animal tissues is not feasible, gel staining methods are required. Silver staining does not at present provide the precise reproducible quantitation required. Hence we have employed a new version of Coomassie Brilliant Blue staining which uses the dye in colloidal form. In this staining process it is essential to expose all areas of all gels uniformly to the colloidal dye solution, which means that each gel should be handled separately. Here we propose a new system of carriers for handling the gels individually, tanks and pumps for ensuring constant temperature and fluid flow, a system for transporting the carriers between tanks, and technology for keeping the concentration of the dye in solution (which is in equilibrium with the colloidal particles) constant.